1. Field of the Invention
The present invention relates to a method for smelting and reducing iron ores and an apparatus therefor, and more particularly to a method for charging and blowing in a smelting reduction process and an apparatus with a constitution suitable for the method.
2. Description of the Prior Art
Smelting reduction method is to be substituted for a blast furnace iron making method and has recently been under research and development to overcome a disadvantages in that the blast furnace iron making method requires not only an expensive construction cost but also a vast construction site.
It is well known that in this smelting reduction method, prereduced iron ores or iron ores, as material, are charged and furthermore carbonaceous material, as fuel and reducing agent, and fluxing material such as lime stone are charged onto a molten metal contained in a smelting reduction furnace, while oxygen is blown in the smelting reduction furnace. Thus, the carbonaceous material is melted into molten metal and C contained in the carbonaceous material is oxidated. CO gas generating from the molten metal are post-combusted into CO.sub.2 gas by means of O.sub.2 gas excessively blown in. Sensible heat of this CO.sub.2 gas is transferred to slag covering the face of the molten metal and to iron grains suspended in the slag and then to the molten metal. In this way, heat necessary for reduction of iron ores are transferred to the iron ores to be reduced and the molten metal is efficiently produced.
However, when in order to reduce the weight of reduction of iron ores, prereduction ratio of the iron ores before transference thereof to the smelting reduction furnace, exhaust gas circulated from the smelting reduction furnace to a prereduction furnace is required to be low-oxidated gas and be of a large amount. For this reason, the combustion ratio of CO in the smelting reduction furnace is lowered and as a result, this prior art smelting reduction method is disadvantageous in that the heat efficiency ratio of the smelting reduction furnace is lowered.